This paper summarizes the results of a research project analyzing communication about global warming among those in the fields of science, politics, and the media in Germany between 1975 and 1995. The methodology of discourse analysis has been applied to investigate the changing perceptions of climate change over time and the ways in which it became an important issue on Germany's political agenda. The first part of the paper will briefly introduce the underlying theoretical assumptions and explain the multiple steps by which data covering a period of two decades have been collected and analyzed. In the second part, the paper will provide the reader with the main research results, indicating the usefulness of distinguishing among the separate discourses on climate change in science, politics, and the mass media. The results suggest that there are specific discourse dynamics common to each of the three spheres, as well as some important disparities among them. These findings will be illustrated by a selection of examples typical of the samples analyzed. Finally, the third part of the paper will discuss the broader theoretical and practical implications of these results, which suggest that modem societies must cope not only with environmental risks but also with the risks inherent in communication.